Cam and groove couplings, also known as cam and groove fittings, cam lock fittings, quick-connect couplings or quick-disconnect couplings, are used to connect two segments of hoses or pipes. A joint is formed by connecting a male coupling with a female coupling. Both male and female couplings are tubular and attach to the ends of a segment of hose or pipe.
The male coupling has a groove on its exterior. The female coupling has an interior diameter sufficiently large to accommodate the male coupling. The female coupling has cam arms that are pivotally mounted between two adjacent parallel lugs. There are typically two pairs of lugs on each female coupling. The two pairs of lugs are usually diametrically opposite each other on the coupling body. Each pair of lugs pivotally supports a respective cam arm assembly. The cam arms pivot on a pin between the lugs to cause the cam to engage the groove. Movement of the cam into the groove locks the male coupling inside the female coupling.
A problem that may arise with such coupling joints is that, when used on vibrating machinery, there is a concern that vibrations can cause the cam arms to open thereby causing decoupling of the joint.
Wire safety clips are inserted through holes in the lugs of the female coupling to prevent the cam arm from opening. One such wire clip is disclosed in U.S. Pat. No. 6,447,016.
A downside of conventional wire clip designs is that extra material is required over the height of the cam arm in order to provide space for the holes through which the clip is inserted. Chains are typically attached to the clips so that the clips are not lost when removed. However, a typical chain-attached clip is still not foolproof because the chain can slip off the clip. Furthermore, in cold weather, it can sometimes be difficult to align the clip with the holes when wearing gloves.
Another conventional approach to this problem is to use an internally locking mechanism such as, for example, a multi-piece spring-loaded lever. U.S. Pat. Nos. 6,015,168 and 5,435,604 and 5,295,717 disclose locking members housed inside the cam arms. However, internal locking mechanisms have their shortcomings. Not only are these costly to tool but their main drawback is they are much weaker. In some cases, e.g. in cold weather applications, the cam arms must be hammered closed. The multi-piece levers tend to be weaker and are prone to breaking.
In view of these shortcomings of the prior art, an improved locking mechanism remains highly desirable.